I am interested in building a flagstone patio to my own house. I have tried to collect as much research as possible and I am getting conflicting advice. My question is this: Is it possible to set the flagstone in mortar and have it hold up without pouring a 4" concrete slab under it first? I am about 95% sure I want to set it "wet" in mortar instead of using sand or crushed granite to fill in the cracks, unless someone on here can tell me why that would be better. Any help would be appreciated. I'm in the landscape maintenance business, but hardscaping is relatively new to me. This is for my house, not a customer's.